1. Brief Description of the Invention
The present invention relates to surface treating articles formed from an organic matrix at least partially coated with or engulfed by an organic binder. The articles may be substantially rigid or flexible, depending on the binder glass transition temperature.
2. Related Art
Surface treating articles formed from an organic polymeric matrix formed of a solid or foamed organic polymer or a nonwoven fiber web find utility in treating a surface to either prepare it for further coatings or to provide a decorative final finish. Burrs and flashings from cast, drilled or punched parts must be removed to produce a desired shape or surface finish. Surface treating articles in the form of wheels, discs, or belts operating at high speeds and high pressures must have sufficient strength and durability when subjected to high use pressure against the workpiece. In some instances, it may be desirous for the article to be flexible to intrude into crevices in the workpiece, in other instances, it may be desirous for the article to be rigid. In addition, the propensity of the article to smear onto the workpiece must be taken into consideration. Smearing is generally considered deleterious.
Polymeric resinous binders used to bond the matrix or to secure abrasive particles within the matrix of such products have generally been either of the hard thermosetting type or the strong, tough elastomeric type. Hard thermosetting resins, such as base catalyzed phenol formaldehyde, are widely used to secure abrasive particles to sheet-like backings or to the fibers of a nonwoven web. Such hard resin binders, while usually having high tensile strength, low elongation at break or failure, and resistance to significant change when subjected to elevated temperatures, are undesirably susceptible to brittle fracture. Strong, tough elastomeric resin binders are more desirable in certain applications which require tougher, more durable surface treatment products. Such elastomeric binders have excellent tensile strength, a high elongation at break, and resistance to brittle fracture but may exhibit significant softening at elevated temperatures as might be encountered when the surface treatment article is urged against a workpiece at high speeds and pressures. Such softening may result in smearing or transfer of portions of the article to the surface of the workpiece, which as described previously is not desired by the user.
The surface treating industry is continually striving for articles which more closely meet user demands. In addition, methods of producing surface treating articles that are kind to the environment, particularly the air and water, are especially strived for.
In light of the above user-driven demands it would be advantageous if surface treating articles could be developed which, by virtue of simple adjustment of binder ingredients, can be tailored to be flexible or rigid, substantially non-smearing at use pressure and temperature, all while using manufacturing processes which do not require use and subsequent removal of volatile organic hydrocarbons.
Chin et al. (U.S. Pat. No. 4,835,210) discloses a process of making an emulsion of a blocked urethane prepolymer and a diamine curative in water. Hoover et al. (U.S. Pat. No. 2,958,593) discloses use of vulcanizates made from reactive precursors dissolved in an organic solvent for making abrasive articles in a lofty organic matrix. Fitzer (U.S. Pat. No. 4,227,350) discloses an abrasive product which employs a tough elastomeric resin binder having excellent tensile strength, a very high elongation at break, and resistance to brittle fracture, but which show significant softening at elevated temperatures. Barnett et al. (U.S. Pat. No. 4,609,380) further advances Hoover et al. and Fitzer with the use of blocked isocyanate end-capped urethane prepolymers and an aromatic diamine in an organic solvent as the prevulcanizate and the addition of specific high glass transition, organic solvent soluble polymers to the vulcanizate precursors to make abrasive articles that cause low smear in high speed grinding or finishing operations. All of the additives that Barnett et al. suggest are insoluble in water. Further, Barnett et al. specifically mention "solvent soluble" (i.e. organic liquid soluble) as a criterion for the selection of the desired high glass transition polymeric additive to make smear-free abrasive articles. Therefore facile or immediate adaptation of the teachings of Barnett et al. for the fabrication of abrasive articles using a substantially aqueous medium for the vulcanizate precursors, such as in Chin et al. will not be immediately feasible.